automating dial-up network

What I want to do is quite simple, but I’ll explain the background, my company does plenty of file transfer to and from other companies, normally this is done through an isdn route but occasionally we have to do it via a PC,
What I want to be ableis to dial up from a pc W2K or NT, via an in built ISDN card, on a scheduled basis. I.e so that 3am when I want to transfer data I can set it up so that a scheduled task will dial-up to the company in question and then a ftp can be performed.